$pull (array update)

  • Article
  • 11/22/2024

The $pull operator is used to remove all instances of a specified value or values that match a condition from an array. This is useful when you need to clean up or modify array data within your documents.

Syntax

{ $pull: { <field>: <value|condition> } }

Parameters

Description
<field> The field from which to remove one or more values.
<value|condition> The value or condition to remove from the array.

Examples

Let's understand the usage with the following sample json.

{
  "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
   "name": "Lakeshore Retail | DJ Equipment Stop - Port Cecile",
  "location": {
    "lat": 60.1441,
    "lon": -141.5012
  },
  "staff": {
    "totalStaff": {
      "fullTime": 2,
      "partTime": 0
    }
  },
  "sales": {
    "salesByCategory": [
      {
        "categoryName": "DJ Headphones",
        "totalSales": 35921
      }
    ],
    "fullSales": 3700
  },
  "promotionEvents": [
    {
      "eventName": "Bargain Blitz Days",
      "promotionalDates": {
        "startDate": {
          "Year": 2024,
          "Month": 3,
          "Day": 11
        },
        "endDate": {
          "Year": 2024,
          "Month": 2,
          "Day": 18
        }
      },
      "discounts": [
        {
          "categoryName": "DJ Turntables",
          "discountPercentage": 18
        },
        {
          "categoryName": "DJ Mixers",
          "discountPercentage": 15
        }
      ]
    }
  ],
  "tag": [
    "#ShopLocal",
    "#SeasonalSale",
    "#FreeShipping",
    "#MembershipDeals"
  ]
}

Example 1: Remove a specific tag from the tag array

db.stores.update(
  { _id: "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5" },
  { $pull: { tag: "#SeasonalSale" } }
)

This query would return the following document.

{
  "acknowledged": true,
  "insertedId": null,
  "matchedCount": "1",
  "modifiedCount": "1",
  "upsertedCount": 0
}

Example 2: Remove all events from the promotionEvents array that end before a certain date

db.stores.update(
  { _id: "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5" },
  { $pull: { promotionEvents: { "promotionalDates.endDate.Year": 2024, "promotionalDates.endDate.Month": { $lt: 3 } } } }
)

This query would return the following document.

{
  "acknowledged": true,
  "insertedId": null,
  "matchedCount": "1",
  "modifiedCount": "1",
  "upsertedCount": 0
}

Limitations

Delete if no limitations/deviations from standard Mongo command, else update as necessary.

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